Buzzing Coming From Speakers??...Don't Believe To Be Ground Loop

[RotelDBA]

Hi,

I recently added a new amp and processor to my home theater setup and now have a buzzing coming from my speakers. It is most definitely a loud buzz as opposed to a hum.

Initially, I thought I have a ground loop issue due to introducing the amp with a three prong plug, but after further investigation I don't believe that to be the case any more. Then I was thinking that there is a problem with the amp (have not completely ruled out). But in the end, it seems like my problem has something to do with my television, but I'm not exactly sure what the actual problem is.

Here is what I have observed with all components in the system connected and plugged in:
If everything is on except the television then everything is perfectly quiet.

If I turn the television on that is when the buzzing in the speakers begins.

The brighter the image on the display gets the worse the buzzing sound gets and the darker the image on the display gets the better (or less) the buzzing sound gets. So, if the television is on, but the screen is completely black then the buzzing is very slight. Then of course if you turn the television off again then the buzz goes away all together.

For testing purposes only, I have tried lifting the ground on the television and amp independently.

I tried turning everything off except the television and the amp with all inputs to the amp disconnected, but still get the buzz until the television is turned off.

Any help or suggestions with resolving this issue would be greatly appreciated.

Thank you in advance.

 

[yettitheman]

Hi,

I recently added a new amp and processor to my home theater setup and now have a buzzing coming from my speakers. It is most definitely a loud buzz as opposed to a hum.

Initially, I thought I have a ground loop issue due to introducing the amp with a three prong plug, but after further investigation I don't believe that to be the case any more. Then I was thinking that there is a problem with the amp (have not completely ruled out). But in the end, it seems like my problem has something to do with my television, but I'm not exactly sure what the actual problem is.

Here is what I have observed with all components in the system connected and plugged in:
If everything is on except the television then everything is perfectly quiet.

If I turn the television on that is when the buzzing in the speakers begins.

The brighter the image on the display gets the worse the buzzing sound gets and the darker the image on the display gets the better (or less) the buzzing sound gets. So, if the television is on, but the screen is completely black then the buzzing is very slight. Then of course if you turn the television off again then the buzz goes away all together.

For testing purposes only, I have tried lifting the ground on the television and amp independently.

I tried turning everything off except the television and the amp with all inputs to the amp disconnected, but still get the buzz until the television is turned off.

Any help or suggestions with resolving this issue would be greatly appreciated.

Thank you in advance.

EMI. Tube tv's suck in this regard. Plug tv into another seperate outlet, power conditioner, or replace the TV with a LCD/Plasma/DLP/Projector/OLED....

 

[RotelDBA]

yettitheman,
Thank you for the reply. The television in question is a 50" Panasonic plasma display. I have tried plugging the television into many different outlets...of course all the outlets have been on the same circuit though. Unfortunately, I don't have the ability to put the any of the components on a separate circuit.

Thanks again for the suggestions.

 

[TLS Guy]

Hi,

I recently added a new amp and processor to my home theater setup and now have a buzzing coming from my speakers. It is most definitely a loud buzz as opposed to a hum.

Initially, I thought I have a ground loop issue due to introducing the amp with a three prong plug, but after further investigation I don't believe that to be the case any more. Then I was thinking that there is a problem with the amp (have not completely ruled out). But in the end, it seems like my problem has something to do with my television, but I'm not exactly sure what the actual problem is.

Here is what I have observed with all components in the system connected and plugged in:
If everything is on except the television then everything is perfectly quiet.

If I turn the television on that is when the buzzing in the speakers begins.

The brighter the image on the display gets the worse the buzzing sound gets and the darker the image on the display gets the better (or less) the buzzing sound gets. So, if the television is on, but the screen is completely black then the buzzing is very slight. Then of course if you turn the television off again then the buzz goes away all together.

For testing purposes only, I have tried lifting the ground on the television and amp independently.

I tried turning everything off except the television and the amp with all inputs to the amp disconnected, but still get the buzz until the television is turned off.

Any help or suggestions with resolving this issue would be greatly appreciated.

Thank you in advance.

Lets me ask you this. If you only have one ground in the system and your TV is on, but completely disconnected from you system you still have a buzz. Is that what you are saying? If that is the case, and I think that is what you said, then this TV is making a lot of radio interference, which is being picked up by the speaker leads and fed back to the amp high gain circuit through the negative feedback. If that is the case, it's time to retire the TV.

 

[RotelDBA]

TLS Guy,

Thank you for the feedback. That is essentially what I am saying. Even with all inputs to the amp disconnected I am still getting buzzing from the surround speakers when the television is on.

This seems sort of strange. What you are saying makes sense my only hesitation is that the television is less than 1 year old and if I put my old receiver back in place then I don't get the buzzing in the speakers.

Another oddity that I just noticed is that the buzzing is not equal in all speakers. The surrounds are the worst, followed by the front left speaker, which produces a little less than the surrounds. The front right speaker produces almost no buzz while the center channel produces pretty much no buzz at all. What makes this even stranger is that from a proximity standpoint the center channel has the closest speaker leads to the television.

As always thank you for the input.

 

[TLS Guy]

TLS Guy,

Thank you for the feedback. That is essentially what I am saying. Even with all inputs to the amp disconnected I am still getting buzzing from the surround speakers when the television is on.

This seems sort of strange. What you are saying makes sense my only hesitation is that the television is less than 1 year old and if I put my old receiver back in place then I don't get the buzzing in the speakers.

Another oddity that I just noticed is that the buzzing is not equal in all speakers. The surrounds are the worst, followed by the front left speaker, which produces a little less than the surrounds. The front right speaker produces almost no buzz while the center channel produces pretty much no buzz at all. What makes this even stranger is that from a proximity standpoint the center channel has the closest speaker leads to the television.

As always thank you for the input.

You have confirmed my theory that this is RF interference. Unfortunately different amp designs vary in their sensitivity to RF. Obviously your Rotel picks it up and rectifies it. The speaker leads act like antennae. The different lengths of the cables affect the strength of the RF signals picked up. That is why the intensity is different in different speakers.

Having said that, your TV must be violating all current RF emission standards for RF radiation. I would complain, but you probably won't get far. What is that TV, so other members can avoid it?

Do you have DIY skills? If you do, I talk you through building RF chokes for each of the speaker outputs. This will ameliorate the problem, but quite likely will not eliminate it entirely. To do that, either the TV or the Rotel has to go.

 

[Rickster71]

I had a similar problem some years back.
I found when I move the receiver further away from the TV,
the noise went away.

 

[RotelDBA]

TLS Guy,

Thank you! Everything you say makes sense and is most likely my problem.

My receiver that does not cause the buzzing is a Rotel. My new amp that does cause the buzzing is a McIntosh.

I do have DIY skill, however I know my knowledge of electrical devices is far from that of other members in these forums.

But, if you are willing and don't mind trying to walk me through creating an RF choke, I am definitely will to try making it.

Thank for your help.

FYI...
The television is a Panasonic TH-50PX60U. This is definitely an issue that I will take up with Panasonic. However, from a picture standpoint I can tell you that if you calibrate the television through the regular menus without having to go into the sevice menu, you would be hard pressed to find a television with a better picture. The only television that I have seen having a slightly better picture was a Pioneer Elite and the improvement was so little that I could never justify the additional cost. Anyone who sees our TV always leaves in awe. For this reason I really hope that Panasonic is willing to do something.

 

[RotelDBA]

Rickster71,
Thank you for your reply. I actually had the same thought a couple of days back and would love to try moving the amp and television further apart, unfortunately my setup is in a living room and I have actually have no space to move things further apart.

And, based on what TLS Guy has said it sounds like this approach would help minimize or even completely resove the issue (depending on how far away they are).

Thank you for the suggestion.

 

[TLS Guy]

TLS Guy,

Thank you! Everything you say makes sense and is most likely my problem.

My receiver that does not cause the buzzing is a Rotel. My new amp that does cause the buzzing is a McIntosh.

I do have DIY skill, however I know my knowledge of electrical devices is far from that of other members in these forums.

But, if you are willing and don't mind trying to walk me through creating an RF choke, I am definitely will to try making it.

Thank for your help.

FYI...
The television is a Panasonic TH-50PX60U. This is definitely an issue that I will take up with Panasonic. However, from a picture standpoint I can tell you that if you calibrate the television through the regular menus without having to go into the sevice menu, you would be hard pressed to find a television with a better picture. The only television that I have seen having a slightly better picture was a Pioneer Elite and the improvement was so little that I could never justify the additional cost. Anyone who sees our TV always leaves in awe. For this reason I really hope that Panasonic is willing to do something.

Oh! That thickens the plot. Most McIntosh amps use auto transformers. Does yours? If so I bet it is the auto transformers picking up the RF, so chokes will not work, likely, as I would assume it is the primary windings picking up the RF. I would not put a McIntosh close to anything that makes RF. You will have to put your electronics at a significant distance form your TV, I can't think of another solution. That will solve it, as Rickster suggests. Sorry, but it's time to rearrange the living room, or get a TV that does not produce RF.

 

[RotelDBA]

TLS Guy,

I have an MC207, which is one of the few McIntosh amps that does not have an auto transformer. It has their dynamic power manager, which adjusts the rails so, that it puts out the same wattage per channel whether using 4 ohms or 8.

It sounds like I may be scr!@#d.


Thank you for the help.

 

[TLS Guy]

TLS Guy,

I have an MC207, which is one of the few McIntosh amps that does not have an auto transformer. It has their dynamic power manager, which adjusts the rails so, that it puts out the same wattage per channel whether using 4 ohms or 8.

It sounds like I may be scr!@#d.


Thank you for the help.

So this is basically a class H amp. The problem is the amp is obviously picking up and rectifying RF. Now, at least for test, you need to move the amp away from the TV. If that cures it, RF chokes will not work. If it does not then, RF chokes are worth a shot. Likely it will come down to rearrange the living room or boot the TV or the Mac.

 

[RotelDBA]

TLS Guy,

Yeah unfortunately the way I have it set up now really is the only way you could set it up because of openings and other physical limitations of the room.

Here is another oddity about all of this. I use an UR MX3000 remote using RF to transmit to IR and have no issues with the functioning of the remote control. In fact, the RF antenna is actually located on the back of the television.

I could be wrong, but it just seems to me like I should get some sort of interference with my remote control. Is my thinking with this flawed?

Thanks.

 

[TLS Guy]

TLS Guy,

Yeah unfortunately the way I have it set up now really is the only way you could set it up because of openings and other physical limitations of the room.

Here is another oddity about all of this. I use an UR MX3000 remote using RF to transmit to IR and have no issues with the functioning of the remote control. In fact, the RF antenna is actually located on the back of the television.

I could be wrong, but it just seems to me like I should get some sort of interference with my remote control. Is my thinking with this flawed?

Thanks.

Unfortunately your thinking is floored. Rf interference is a complex problem.

If you can't move things, you will have to change one unit or the other.

 

[yettitheman]

I've had a similar problem with my P2001 hooked up to my Dimensia pre-amp...

Tv on = fuzzy static
Tv off = sounds fine

I ended up solving quite a bit of issues by connecting my pre-amp to my amp with Straightwire Chorus RCA cables (seeing as I got a steal on them). They are US made (from what I remember), very heavily shielded and insulated from EMI and RFI. It might be worth a shot to upgrade all of your interconnects with cables from Monoprice or Blue Jeans (both very well reputable companies) and look into shielded speaker cables (if they make such a thing).

 

[TLS Guy]

I've had a similar problem with my P2001 hooked up to my Dimensia pre-amp...

Tv on = fuzzy static
Tv off = sounds fine

I ended up solving quite a bit of issues by connecting my pre-amp to my amp with Straightwire Chorus RCA cables (seeing as I got a steal on them). They are US made (from what I remember), very heavily shielded and insulated from EMI and RFI. It might be worth a shot to upgrade all of your interconnects with cables from Monoprice or Blue Jeans (both very well reputable companies) and look into shielded speaker cables (if they make such a thing).

I have done some checking. I think the problem is likely your Panasonic TV.

I say this because your amp is available in the EEC. Now some years ago the EEC passed draconian regs as to how much RF a device could produce and how much it could be affected by RF. Now the MAC MC 207 obviously passed, unless they are making a separate version for the EEC. Now you might want to check with MAC on that. If the amps are different, make them do the mods they do to pass the EEC regs.

Now the TV I can't tell, because the broadcast systems are totally different in Europe, so TV's have to be different. My hunch is that the RF radiation from the Panny is grossly excessive.

Now I have pulled your owners manual off the net. Now what are you driving the MAC MC 207 with? Are, or can you, use the balanced inputs?

Now you have to solve this, so you can't bury your head in the sands. You need to move the amp for a test and see if the buzz stops and how far away you have to move it. If the buzz stops connect it to the preamp and see what happens. If the buzz stops, it is no good using speaker lead chokes, if it does not, speaker lead chokes might work. I'm assuming you get a buzz whether the preamp is connected or not, in the current location, is that correct? If that is so changing cables will not help.

You can't use screened speaker cables by the way, as the capacitance is too high. You can run the cables in steel conduit though.

Can you post pictures of your set up? This is important as you may be able to move the amp to one side. RF decreases by the square of the distance form the source. Getting some distance is job one.

If you can't get distance and the MAC is picking up the RF within the case and not via leads, ask MAC if they will do some mods to reject RF. It involves looking at suspect ares of the circuit, going round with the scope and finding the ares of RF penetration and deciding how to block them. A competent service tech could do it, but unless MAC did it it would void the warranty.

Changing a year old Plasma TV should be a last resort. The replacement might also cause problems. Since your dealer just sold you this amp, may be he can find you a brand that will not be so susceptible to RF penetration?

Any way these are the ideas I have right now for your difficult problem. Get back with the further information requested and the best plan will likely become apparent.

 

[RotelDBA]

TLS Guy,

Let me know if I miss anything and I apologize for the slow reply. I needed to wait until I got home so I could attach pictures.

I'm driving the MC207 with an Anthem D2 preamp processor. I am currently using the balanced inputs.

I do get the buzzing whether the preamp is connected or not. I may be able to put the amp on the floor in the dining room to move it away from the television. I will have to see what I can do about the speaker wires since most of them are too short to move the amp anywhere else, but I may be able to pull something together.

I attached pictures of my setup, so you can see what I'm working with.

Thanks.

 

[TLS Guy]

TLS Guy,

Let me know if I miss anything and I apologize for the slow reply. I needed to wait until I got home so I could attach pictures.

I'm driving the MC207 with an Anthem D2 preamp processor. I am currently using the balanced inputs.

I do get the buzzing whether the preamp is connected or not. I may be able to put the amp on the floor in the dining room to move it away from the television. I will have to see what I can do about the speaker wires since most of them are too short to move the amp anywhere else, but I may be able to pull something together.

I attached pictures of my setup, so you can see what I'm working with.

Thanks.

Those pictures and the further information is very helpful. That amp is quite a long way from the TV. I think most likely there is something seriously wrong with that TV. I doubt it is the amp as it is on all channels, unless the amp is a dud design. I did note there is a lot of circuitry on the high gain sections, including that power guard, which I think is a standard peak limiter. The more garbage you have in the high gain sections the more vulnerable the unit will be to RF penetration. If the problem persists at a greater distance, I would check the house wiring, in case this is being transmitted via the AC due to neutral gouging. If the buzz does not decrease in volume as you increase the distance from the TV, then you may well have a house wiring problem. You need to check that the outlets are correctly wired. The next thing is to make sure there is no more than 0.5 volts and certainly no more than 1 volt between neutral and ground. If there is you need an electrician to correct the problem.

If the power is OK then I would contact Panasonic and demand to evaluate a replacement TV. If the replacement causes trouble, I would get on to McIntosh and see if they will admit to this problem in other set ups. If you can't get satisfaction, then tell your dealer these units are duds and get a different amp. I did find out McIntosh are now owned by Denon/Marantz and that they are cheapening the units up. Typical! We can't seem to do anything for our selves any more, and price points are driving fine old Western firms to extinction. Personally I would tax these far Easter units until they cheapest are $3000 a piece! I have always hated this far Eastern junk, but even I have been forced to place a few units of Far Eastern manufacture in my rig. I keep it to the bare minimum!

 

[RotelDBA]

TLS Guy,

Thank you for all your help. It was because of all your talk about IR interference that I focused my thoughts on that aspect and continued to think about what could be causing the TV to give off that much interference.

This morning it dawned on my what could be causing the TV to generate that much interference and I ended up being right and was able to fix my problem.

If you look at the pictures of my system what you can't see is that the TV is mounted to a stand made for flat panel TV's. In fact the stand is a big, all metal pillar.

So, this morning I started wondering if the stand could be acting like a big antenna for the RF interference and I'm happy to say that is what the problem ended up being.

When I unbolted the TV from the stand and stood it on a box right next to the amp (inches away) I no longer got the buzzing sound. In fact, I was able to re-mount the TV and still not get the interference. It wasn't until I actually started re-tightening the first bolt and making solid contact between the mounting bracket and the mount that the buzzing started coming back.

As I continued to re-tighten each of the four bolts the buzzing continued to get louder and louder until it was all the way back to where it was originally.

So, I took a ride to Lowes and purchased eight nylon washers for $2. I put one on each bolt between the mounting bracket and the mount, and I put one on each bolt between the mount and the locking nut.

Presto! No more buzzing and other than the time my time it cost me $2. I was pretty happy that it ended up being something that could be easily fixed for very cheap.

Thank you again for all your help.

 

[TLS Guy]

TLS Guy,

Thank you for all your help. It was because of all your talk about IR interference that I focused my thoughts on that aspect and continued to think about what could be causing the TV to give off that much interference.

This morning it dawned on my what could be causing the TV to generate that much interference and I ended up being right and was able to fix my problem.

If you look at the pictures of my system what you can't see is that the TV is mounted to a stand made for flat panel TV's. In fact the stand is a big, all metal pillar.

So, this morning I started wondering if the stand could be acting like a big antenna for the RF interference and I'm happy to say that is what the problem ended up being.

When I unbolted the TV from the stand and stood it on a box right next to the amp (inches away) I no longer got the buzzing sound. In fact, I was able to re-mount the TV and still not get the interference. It wasn't until I actually started re-tightening the first bolt and making solid contact between the mounting bracket and the mount that the buzzing started coming back.

As I continued to re-tighten each of the four bolts the buzzing continued to get louder and louder until it was all the way back to where it was originally.

So, I took a ride to Lowes and purchased eight nylon washers for $2. I put one on each bolt between the mounting bracket and the mount, and I put one on each bolt between the mount and the locking nut.

Presto! No more buzzing and other than the time my time it cost me $2. I was pretty happy that it ended up being something that could be easily fixed for very cheap.

Thank you again for all your help.

Well done! We will have to bear that in mind when this problem comes up next. I still think you should let Panasonic know about this. The stand bolts to the the TV chassis, and the chassis should not be in contact with any parts potentially radiating RF. I feel there may be something wrong with the wiring of that TV (something touching the chassis that shouldn't be), or else there is bad design someplace.

What is going on absolutely should not occur. I did have the feeling that the Panny was most likely the rogue unit, and you proved it. Thanks for the feedback.